TROPHIC INTERACTIONS AT NEUROMUSCULAR JUNCTIONS

描述：（改编自申请人的摘要） 这项研究的目的是从分子角度了解突触是如何形成的 以及它们在成年动物中是如何维持的。 这些事件可以在脊椎动物身上进行非常精确的研究 神经肌肉接头是一种突触，其功能、形态和 生化表型比任何其他化学物质都更好地理解 突触 这项建议的重点是ARIA，一种多肽， 基于其乙酰胆碱受体诱导活性纯化， 胚胎骨骼肌管 ARIA可能在开发和 成熟的连接，以促进ACh受体的合成， 在突触后肌肉膜中积累。 一个直接目标是 该建议是研究ARIA的处理：如何合成 在运动神经元中调节，如何转运到运动轴突 终端和它是如何显示在突触间隙。 膜 将详细研究结合位点，以确定哪种类型 与生理反应最相关。 另一个目标是 表征肌肉膜中的ARIA结合蛋白，以及其他 细胞外基质中的结合蛋白，可以调节其 行动上 另一组重要的实验旨在定义 ARIA在终板发育不同阶段的作用谱。 这种强有力的分化因子可以调节几个基因， 突触前和突触后膜上的离子通道， 突触后的细胞质，和蛋白质，是注定要为 细胞外基质 简而言之，它可以是一个主开关， 调节突触特异性基因表达。 ARIA是作为一种 跨膜前体（proARIA）和几个可变剪接的 已经发现了同种型。 这项研究的最终目标是， 因此，为了准确地确定哪些亚型在运动中表达， 神经元和每个神经元的确切作用。 计划中的实验 依赖于重组DNA、生物化学、电生理和 形态学技术 确定ARIA为第一批 在神经肌肉接头处起作用的营养因子 关于运动与营养之间的双向关系的研究， 神经元和它们周围的突触伙伴。 纯化ARIA 从大脑中，它很可能发挥强大的营养作用， 在中枢神经系统和周围神经系统中。 来看 它在整个神经系统的胆碱能神经元中的位置， 在一些非胆碱能细胞中，我们在神经肌肉接头的研究 将立即进口的研究正常和异常 CNS的发展。

DESCRIPTION: (adapted from Applicant's Abstract) The long range goal of this research is to understand, in molecular terms, how synapses form during embryonic life and how they are maintained in adult animals. These events can be studied with great precision at the vertebrate neuromuscular junction, a synapse whose functional, morphological and biochemical phenotype is understood better than any other chemical synapse. This proposal is focused on ARIA, a polypeptide that was purified based on its acetylcholine receptor inducing activity in embryonic skeletal myotubes. ARIA probably acts at developing and mature junctions to promote the synthesis of ACh receptors and their accumulation in the postsynaptic muscle membrane. One immediate goal of the proposal is to study the processing of ARIA: how the synthesis is regulated in motor neurons, how it is transported to the motor axon terminals and how it is displayed in the synaptic cleft. Membrane binding sites will be studied in detail to determine which type correlates best with physiological responses. Another goal is to characterize ARIA binding proteins in the muscle membrane, and other binding proteins in the extracellular matrix that may modulate its action. Another important set of experiments is designed to define ARIA's spectrum of action at various stages of endplate development. This potent differentiation factor may regulate several genes that encode ion channels in the presynaptic and postsynaptic membrane, proteins in the postsynaptic cytoplasm, and proteins that are destined for the extracellular matrix. It may, in short, be a master switch that regulates synapse specific gene expression. ARIA is synthesized as a transmembrane precursor (proARIA), and several alternatively spliced isoforms have been uncovered. A final goal of this research is, therefore, to determine exactly which isoforms are expressed in motor neurons and the precise role for each one. The planned experiments depend on recombinant DNA, biochemical, electrophysiological and morphological techniques. Identification of ARIA as one of the first trophic factors operating at the neuromuscular junction opens new areas of study regarding the two-way, nutritive relationship between motor neurons and their synaptic partners in the periphery. ARIA was purified from the brain, and it is likely that it exerts powerful trophic effects in the central nervous system as well as in the periphery. Judging from its location in cholinergic neurons throughout the nervous system and in some non-cholinergic cells, our studies at the neuromuscular junction will have immediate import for studies of normal and abnormal development in CNS.